Garden Talk: June 9, 2005

From NGA Editors

The Best Salvias For Hot Summers

Salvias are one of the most commonly grown bedding plants across the country. They grow and flower quickly, producing spikes of red, white, pink, blue, and purple flowers all summer long. However, in hot summer areas, the high temperatures can cause damage to the plant and a reduction in flowering.

Although all salvias are considered heat tolerant, there is some variation in performance, depending on the variety. Researchers at Louisiana State University selected two of the most popular salvia series -- Vista and Sizzler -- and tested their performance under high temperatures. Three-week-old seedlings were exposed to 3-hour-long treatments at high-temperatures (86, 95, 104 and 113° F) every three days until flowering. Both salvia series died when exposed to 113° F treatments. However, at the 95 and 104° F levels, Vista cell membranes were less damaged and the plants had thicker, more erect leaves and less leaf scorching.

For gardeners growing bedding plants in hot summer areas, the Vista salvia series would be the best choices to grow. Researchers plan on using this test to trial other bedding plant lines to determine their ability to withstand high heat.

Plastic Mulch Repels Pests

Tomatoes, peppers, melons, squash, and cucumbers are popular summer garden vegetables. However, they also are subject to many insects and diseases. Gardeners have used colored plastic mulch to help heat the soil and increase production on these crops, but now it appears that colored mulch also can help protect plants again insects and disease.

The SRM-Silver mulch is similar to black plastic mulch but it has a silver coating on one side. As certain light wavelengths are reflected into the sky by the mulch, flying insects --such as whiteflies and aphids -- are deterred from landing on the plants. Not only do these insects feed on your crops, they also transmit diseases, such as viruses. So the incidence of disease also is lower in plots where this mulch was used.

Although the SRM-Silver plastic mulch heats the soil more slowly compared to red or black plastic mulch, it still conserves soil moisture and controls weeds like other plastics. In addition, in some tests the tomatoes grown in the SRM-Silver mulch actually outyielded those grown in red or black plastic mulch.

Organic Fire Ant Control

Fire ants are a major pest in lawns and gardens across much of the country. Now there is an effective organic control that will help eliminate these harmful pests that's safer for the environment than traditional control methods.

Spinosad is derived from the fermentation of a naturally occurring bacterium. This organic insecticide is highly effective at low rates, can last for weeks in the soil, and has less impact on predatory, beneficial insects than non-organic chemicals. Spinosad attacks the nervous system of the ants, causing them to eventually be paralyzed and die. It is also effective on thrips and caterpillars.

Spinosad works best when broadcast over a large area and then applied as a drench on individual mounds in high-traffic areas. Apply Spinosad when the weather is warm (above 65&deg F), but not hot. During the hot part of the summer, apply Spinosad in the late afternoon or early evening when rain is not expected for the next 24 hours. Ants should start dying within one day, and you should notice a decrease in ant activity in the mound soon after.

Kudzu Reduces Alcohol Consumption

The "vine that ate the South" may have a positive side after all. Researchers at the McLean Hospital in Belmont, Massachusetts, investigated kudzu as a treatment to curb excessive drinking. Scientists knew kudzu was used in ancient China to decrease alcohol consumption, so they gave a specially prepared herbal extract containing kudzu to 14, 24-year-old men and women. After determining how much these young adults normally drank, the researchers gave half of the patients tablets containing kudzu, and the other half placebo tablets.

Alcohol consumption was cut almost in half in the group that received the kudzu tablets. Another study at Harvard Medical School also suggests kudzu's potential for helping heavy drinkers reduce their craving for alcohol.

Unfortunately, commercial herbal preparations won't do the trick. They typically contain only 1 percent kudzu, while researchers in the McLean Hospital study manufactured a 30 to 40 percent kudzu extract for their test. Researchers suggest a drug containing kudzu may eventually be on the market to help alcoholics.